Gm Global Technolgoy Operations, Inc.

David Morganroth

Marek L Wilmanowicz

Paul Skupinski

Sheryl Page

An improved powertrain control minimizes output torque disturbances due to garage shifting. Under certain predefined conditions, garage shifts to the forward or Drive range are carried out by initially commanding a shift to an upper forward gear ratio having a relatively low torque advantage, and then commanding a shift from the upper forward gear ratio to a lower forward ratio that is ordinarily used to launch the vehicle. The shift from the upper gear ratio to the lower gear ratio is initiated when the initial shift is substantially complete or when a predetermined period of time has elapsed since shift initiation. Engine management controls are also used to reduce the transmission input torque during garage shifts to both forward and reverse ranges.

Garage shift control for a motor vehicle automatic transmission

A method is provided for determining an acceptable torque level to be applied to at least one clutch pack (of an automobile) which includes the requirement of internal slip to transmit torque. The automobile includes a plurality of wheels. A velocity is sensed at each of the plurality of wheels of the automobile. A speed information value is calculated. The speed information value is a function of the sensed velocities at each of the plurality of wheels. The speed information value is then compared with a calibration table. Finally, the acceptable torque level is determined primarily from the calibration table based on the speed information value.

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Gaines, MI, United States of America

David Morganroth